Qualitative Polymerase Chain Reaction Test Research Articles

Multiplex testing for Factor II and Factor V mutations in thrombophilia: technical verification and clinical validation of the cobas\xae Factor II and Factor V test

Laboratory testing for thrombophilia is complicated but essential for diagnosis. In 2017, the cobas® Factor II and Factor V Test (cobas F2F5 test) was launched for use with the cobas z 480 analyzer. This qualitative polymerase chain reaction test enables multiplex Factor II and Factor V testing with flexible reporting and workflow efficiency. Here, we report the results from studies investigating the performance of the cobas F2F5 test. Technical performance verification, clinical validation, external laboratory performance, and workflow comparison studies were performed. Fresh and frozen whole-blood and genomic DNA (gDNA) samples were tested, and several manual and automated DNA isolation methods were used. Bidirectional Sanger sequencing was used to verify genotypes identified by the cobas F2F5 test. One hundred percent agreement between the cobas F2F5 test and Sanger sequencing was observed for all genotypes. An external laboratory using remnant clinical samples also yielded 100% agreement between cobas F2F5 test results and their routine testing method. The cobas F2F5 test reduced the total sample processing time compared with the LightCycler® 1.2 platform (98.6 vs 420.2 min; 96 samples). Hemoglobin, extraction buffer, and ethanol contamination of the gDNA sample can lead to invalid results. The cobas F2F5 test has a high degree of accuracy for identification of Factor II and Factor V genotypes. This multiplex testing with short sample processing time can reduce handling errors and increase efficiency. Both manual and automated DNA isolation methods can be used with the cobas F2F5 test.

Quality Assessment of Cytomegalovirus PCR Testing at an Academic Tertiary Referral Hospital

BackgroundCytomegalovirus (CMV) Polymerase chain reaction (PCR) test is a valuable tool for diagnosis and therapeutic monitoring of CMV infection. Academic medical centers with a high volume of organ transplant and immunosuppressed patients often utilize CMV quantitative and qualitative PCR testing. CMV qualitative PCR typically does not alter clinical management, and positive CMV qualitative test often needs follow up quantitative test. Despite its lack of usefulness, CMV qualitative PCR is often over-ordered and may unnecessarily raise the cost of hospitalization. We evaluated utility of CMV PCR testing at a tertiary care medical center.MethodsWe reviewed CMV PCR testing done from June 2015-November 2016 at Hahnemann University Hospital in Philadelphia, PA. CMV qualitative test was performed at LabCorp and CMV quantitative test was done at Focus Labs. Data collected included demographics, length of stay, and immunosuppression. Selected patients had either CMV qualitative PCR positive without follow up quantitative PCR, or negative CMV qualitative PCR with unnecessary CMV quantitative PCR ordered.ResultsWe evaluated 226 CMV PCR test results including 162 qualitative and 64 quantitative CMV PCR in 139 patients. 39 (28%) patients had superfluous CMV testing. Mean age was 52.6 years, 61% were male, 46% were African American. Mean length of stay was 24 days. A half (N = 19,49%) were immunocompromised. 28 (17.2%) results were positive for CMV qualitative PCR, 7 (25%) of whom follow up CMV quantitative PCR were not sent. Thirty-two patients had negative CMV qualitative testing yet had CMV quantitative PCR sent. Six had redundant CMV quantitative PCR tests within 7 days likely resulting from delayed result report from send out. After performing cost analysis, these unnecessary tests would have saved $3930.ConclusionIn our cohort, significant unnecessary CMV testing resulted in increased health care cost and patient discomfort. Positive Qualitative CMV PCR without Quantitative testing impairs diagnosis and treatment follow up. Given complicated testing algorithm and limited value of CMV qualitative PCR testing in the adult population, we plan to simplify CMV testing to quantitative only and perform in house testing to shorten result time.Disclosures All authors: No reported disclosures.

Human parvovirus B19 infection in a renal transplant recipient: a case report

BackgroundParvovirus B19 presents tropism for human erythroid progenitor cells, causing chronic anemia in organ transplant recipients, due to their suppressed humoral and cellular responses. Diagnosis may be achieved through serological tests for detection of anti-B19 antibodies. However, renal transplant recipients are not routinely tested for parvovirus B19 infection, since there is scanty data or consensus on screening for B19 infection, as well as for treatment or preventive management of transplanted patients.Case presentationHerein we report a kidney transplant recipient, who was unresponsive to treatment of severe anemia, and presented hypocellular hematopoietic marrow, megaloblastosis and hypoplasia of erythroid lineage with larger cells with clear nuclei chromatin and eosinophilic nuclear inclusions. This patient was seropositive for Epstein-Barr and Cytomegalovirus infections and negative for anti-parvovirus B19 IgM and IgG antibodies, although symptoms were suggestive of parvoviruses infection. A qualitative polymerase chain reaction testing for B19 in serum sample revealed positive results for B19 virus DNA.ConclusionThis case report suggests that the diagnostic process for parvovirus B19 in renal transplant recipients should include a polymerase chain reaction assay to detect B19-DNA, since specific serological tests may be unreliable given their impaired humoral responses. These results also indicate the importance of considering parvovirus B19 infection in the differential diagnosis of persistent anemia in transplanted patients.

Crimean-Congo hemorrhagic fever in a dengue-endemic region: lessons for the future

Crimean-Congo hemorrhagic fever and dengue hemorrhagic fever are endemic in Pakistan. However, the overlap of geographic distribution and early clinical features between the two conditions make a reliable diagnosis difficult in the initial stage of illness. A 16-year-old boy presented with a history of hematemesis and high-grade fever. A preliminary diagnosis of dengue hemorrhagic fever was made and supportive treatment was instituted; however, the patient continued to deteriorate clinically. Dengue IgM antibody testing was negative on the third day of admission. Qualitative polymerase chain reaction test for Crimean-Congo hemorrhagic fever viral RNA was sent but the patient expired shortly after the results became available on the sixth day of admission. Considerable resources had to be expended on contact tracing and administration of ribavirin prophylaxis to all the health-care workers who had come in contact with the patient. It is crucial that Crimean-Congo hemorrhagic fever be recognized and treated at an early stage because of longer term financial and health implications for contacts such as health-care workers in the setting of a developing country. Increased surveillance of dengue and Crimean-Congo hemorrhagic fever cases is warranted for the derivation of reasonably reliable, cost-effective and prompt predictors of disease diagnosis. These predictors can help guide future decisions in the management of similar cases. Ultimately, such a strategy may translate into better cost containment in resource-poor settings. Institution of ribavirin prophylaxis in selected patients also merits consideration.

Extended Treatment Duration for Hepatitis C Virus Type 1: Comparing 48 Versus 72 Weeks of Peginterferon-Alfa-2a Plus Ribavirin

The treatment of patients infected with hepatitis C virus (HCV) type 1 remains a challenge necessitating innovative strategies to improve treatment outcome. The extension of treatment duration beyond 48 weeks is one possible strategy to address this problem. The efficacy and safety of 48 weeks (group A, N = 230) vs 72 weeks (group B, N = 225) of treatment with pegylated-interferon-alfa-2a (180 microg/wk) plus ribavirin (800 mg/day) were studied in treatment-naive patients with HCV type 1 infection. On-treatment and sustained virologic response (SVR) 24 weeks after stopping treatment was assessed by qualitative reverse-transcription polymerase chain reaction (sensitivity 50 IU/mL). Overall, no significant differences could be observed in the treatment outcome between both groups. End-of-treatment and SVR rates in groups A and B were 71% vs 63% and 53% vs 54%, respectively. Patients with undetectable HCV-RNA levels already at weeks 4 and 12 had excellent SVR rates ranging from 76% to 84% regardless of treatment group, whereas patients shown to be still HCV-RNA positive at week 12 achieved significantly higher SVR rates when treated for 72 instead of 48 weeks (29% vs 17%, P = .040). A particular benefit from extended treatment duration was seen in patients with low-level viremia (<6000 IU/mL) at week 12. The frequency and intensity of adverse events was similar between the 2 groups. Extended treatment duration generally is not recommended in HCV type 1 infection and should be reserved only for patients with slow virologic response defined as HCV-RNA positive at week 12 but negative at week 24.

Development of a novel approach for the production of dried genomic DNA for use as standards for qualitative PCR testing of food-borne pathogens

As part of a multi-centre European project, FOOD-PCR, the feasibility of a novel approach for production of dried bacterial DNA that could be used as certified reference materials (CRM) was assessed. Selected strains of Salmonella typhimurium, Listeria monocytogenes, Escherichia coli O157, Campylobacter jejuni and Yersinia enterocolitica were used to produce genomic DNA (gDNA). These preparations gave support to method development for qualitative polymerase chain reaction (PCR) detection methods for food-borne pathogens. Purified gDNA was transformed into stable and dry gDNA by using polypropylene vials as carrier and applying a vacuum-drying technique. The gDNA preparations were shown to be sufficiently stable under ambient transport conditions without cooling and proved to have long-term stability at 5°C of at least 22 months. The dried DNA was easily reconstituted by addition of distilled water then gentle shaking. These studies have shown that production of stable and dry bacterial gDNA material is feasible and could help satisfy the increasing need for certified reference DNA positive control samples in the field of PCR testing for detection and verification of food-borne microbial pathogens.

Epstein-Barr virus monitoring in paediatric renal transplant recipients.

Prospective Epstein-Barr virus (EBV) surveillance post transplant was undertaken by qualitative polymerase chain reaction testing for EBV DNA in plasma so as to detect EBV viremia as early as possible and thereby attempt to pre-empt post-transplant lymphoproliferative disease by reduction of immunosuppression. Forty-three children (46 transplants) were followed for a median (range) of 15.5 (3-25) months. Thirty-one children (67%) were EBV seropositive pre transplant. Twenty children (44%) developed EBV viremia; of these 9 (60%) were seronegative and 11 (36%) seropositive recipients. Primary infection developed later (median difference 14.2 weeks, P=0.009), was more likely to be symptomatic (odds ratio 2.91, 95% confidence interval 0.95-4.88) and associated with a rise in serum creatinine (odds ratio 6.13, 95% confidence interval 4.13-8.13) than reactivation disease. There was a higher incidence of EBV disease in children receiving quadruple therapy and tacrolimus (odds ratio 13.2, 95% confidence interval 11.5-14.9) compared with those given cyclosporin-based immunosuppression. Immunosuppression was reduced when EBV infection was detected. All children became asymptomatic and renal function returned to normal by a median (range) of 17 (6-52) days, although mild relapses occurred in 3 children. Regular EBV surveillance allowed prompt reduction of immunosuppression and was associated with a good outcome in this group of children.

A light in the darkness: Predicting outcomes for congenital cytomegalovirus infections

A light in the darkness: Predicting outcomes for congenital cytomegalovirus infections